As 2011 draws to a close, a comet that hadn't even been discovered a month ago is emerging as the celestial sensation of the year. NASA's Kepler spacecraft might be redefining how we view extrasolar planets, but Comet Lovejoy (C/2011 W3) likewise has forever altered our notion of what happens to comets as they near the Sun.
This 11th-hour interloper not only survived its December 16th perihelion (a scorching 116,000 miles from the Sun's surface), but in the days afterward it also held together and reformed its dust and gas tails. Armchair astronomers around the world watched anxiously as the comet distanced itself from the Sun in image sequences taken by orbiting spacecraft. And for those lucky enough to live deep in the Southern Hemisphere, viewing vicariously was soon no longer necessary.
Barely a day after perihelion, discoverer Terri Lovejoy managed to snap images of his namesake in daylight, when he estimated its brightness at roughly -1 in magnitude. Its brightness has fallen off somewhat in the days since, to perhaps 4th magnitude, but many observers now report being able to see Comet Lovejoy with unaided eyes in the predawn sky, its tails stretching upward into Scorpius. As of this morning the comet's nucleus was about 17° from the Sun, an elongation that will grow rapidly to 24° by Christmas Day and 40° by New Year's Eve.
"At long last the skies are clear in the Canberra region," reported Australian observer Dave Herald earlier today. "The nucleus for Lovejoy doesn’t rise for another half hour. But already the tail is visible to the naked eye, extending a full 10° above the horizon. The surface brightness is similar to the Magellanic clouds — even though they are higher in the sky."
Watching and photographing the comet from New Zealand's North Island, Ian "Coops" Cooper noted, "We always knew that this would be the day. Once the coma cleared the brighter part of astronomical twilight, we were in with a grin. Tail now out to 18°!" — and here is his proof!
Meanwhile, members of Brazil's Grupo Nevoeiro astronomy club scrambled to find a dark-sky site outside the city of Curitiba. Fernando Lopes managed to capture several images in the growing twilight that revealed Comet Lovejoy's thin gas tail. "Wonderful show — unforgettable moment," he exults.
In fact, the comet has now been viewed by observers with arguably the best-possible vantage: the International Space Station. Yesterday, ISS commander Dan Burbank captured a view of the comet rising from the color predawn twilight and airglow hugging Earth's limb. He posted a quick view of his snapshot via Twitpic, and within the hour NASA has released the full-resolution view. What a sight!
All the excitement over Comet Lovejoy has almost — but not quite — caused me to forget that we northern skywatchers are once again relegated to the sidelines by a wonderful "broom star" gracing southern skies. It's been five years, but I'm still grouchy that I didn't get to view Comet McNaught, C/2006 P1, in all its feathery glory. (So too is my science-writing colleague Daniel Fischer, who's still steamed that NASA managers didn't send the Space Station crew a head's up about that gorgeous cosmic visitor.)
Well, I can always dream: Seiichi Yoshida's list of future visual comets hints that one of PanSTARRS's comets, C/2011 L4, could conceivably blaze to magnitude 0 when it peaks in mid-March 2013. For those who care, that's just 448 days from now!